Flutterby™! : Tandem toys 2004-07-07 15:59:48.184848+00

Tandem toys

2004-07-07 15:59:48.184848+00 by Dan Lyke 7 comments

Okay, new category: Dan's Life - Tandem Toys, bike parts and components that I can't justify yet but want to keep track of. For starters:

The Rohloff Speedhub (in German, the Rohloff USA page is frame based and doesn't allow deep linking) is a 14 speed hub with all internal gearing. It doesn't have the overlap of a standard derailleur system, so they claim similar gear ratio coverage with less maintenance and adjustment. Chris Timm raves about it for off-road tandem riding, Kinetics in the U.K. has a bunch of drawings. In the $1000+-10% range.
Probably sooner would be a good tandem intercom system like the Tandem-Com, unless I get a little bit better with op-amps and end up building one one weekend. But the real challenge is finding a quality wind-resistant mic, and the hassles of that make a small premium worthwhile.
SPD compatible sandals. Shimano or "Lake" seem to be the brands of note.

The Rohloff hubs have the one problem of being less sturdy torque-wise than conventional derailleurs. Make sure you're not going to be hauling more weight than it can handle. I can't use a Rohloff on my trike because I'd tear it apart - low gearing plus heavy loads means mucho torque.

The Shimano SPD sandals are nice. I got mine at a November "we're going to mark all the sandals WAY down" sale a couple years back. If you should ever happen to ride in cold, you can extend the straps and they'll even fit over Sorel liners (think 1cm thick felt booties), and if it's wet, you can baggie your feet under the sandals and remain pretty comfortable. Recommended.

tandem bikes sure have come a long way from when grandma & grandpa rode their tandem on the beach!

Dave, although I see the low gearing as a warranty specification (and I need to get out and count teeth to figure out where we are right now so that I know where I want to go, even though this is all still totally wishfull thinking), I haven't found any reports on the 'net of anyone who's actually had a hub fail. And in the process I've found some reports of some pretty extreme rides, some of which have chewed standard derailleurs (although those were replaceable in parts).

Which brings me to another question I've wondered about: My only 'bent experience has been the tandem recumbent quadricycle I built for Burning Man

and one loop around the block from a guy who saw me riding it from his bike and said "wanna try this one?". It would seem to me that a 'bent rider could generate more instantaneous power because you've got something to push against rather than just being limited by the weight of the rider plus what minimal force you can get by hauling up on the handlebars; is this part of the problem.

Polly, bikes in general have come a long way since grandma & grandpa... And yet, when you get into the higher end, away from indexed shifters and such and back to the parts people who get "in tune" with their bike use, it seems like the only things that've changed in the past 30 years or so are materials.

Somebody is still making non-index shifters? There is hope! It's been many years since I worked in a bike shop (index shifters were just becoming popular), but I was under the impression that they'd definately taken over.

#Comment Re: power on a 'bent made: 2004-07-09 14:11:27.87169+00 by: DaveP

I'm not sure about the instantaneous power thing. My feeling is that I could generate about as much power on an upright bike if I was clipped in, but I'm not sure about that. A major component in my sprinting start is pulling with one foot while pushing with the other. I don't think I pull harder against the frame on my 'bent than I would against gravity on an upright. But I haven't even thought to measure it.

In general, I know I can't sustain anything like the power I can produce launching into a sprint. On flat ground I can outrun upright riders (in much better shape than me) for about a mile in a full-out sprint, but on hill-climbs, I gear down and spin and get passed like crazy by people Lance-dancing up the hill on their upright.

The other problem with 'bents is that they typically have smaller drive wheels, often a 20 inch, instead of a 26 or 27. That throws an added complication into the calculations, and I figured that even with my desire to be able to "ride my trike up a tree", I could maybe be within the warranty range on a big rear wheel, while I wouldn't on a 20.

Mostly I wanted to point it out as a concern, since it's one of the factors that kept me from buying a Rohloff hub. I would have probably used it with the same widely-spaced triple chainring I currently use, for an awesome range of gear-inches, but that would have definitely voided the warranty, and after talking with the Rohloff rep, I decided I didn't want to be the first guy to tear one apart.

For what it's worth for your calculations, when I'm riding my trike, I'm typically hauling between 350 and 400 lbs, counting trike (35#), rider (300#) and miscellaneous gear (up to four arkel panniers hung behind me).

Finally, Rohloff has continued to improve the guts of their hubs. My concerns were based on the model they were selling winter 2001-2002, and I understand that they've improved things since then, even if the warranty doesn't reflect that.

The thing that was pointed out in one of the threads about failures was that drive wheel size really didn't matter because if you're looking at failure modes (rather than wear modes) you're concerned about stalled torque, and in that case wheel size doesn't matter.

We're at similar loads on the tandem, when we've got gear on probably closer to 400lbs. Thanks for noting that, it's something I wasn't thinking about when I was getting all excited about the notion of sealed shifting.